The present invention relates to the removal of debris and unwanted contaminant material from shards so that the shards may be cleaned and prepared for use in refabricating objects. In this sense, shards genrally mean fragments of objects, such as glass, thermoset materials, ceramics, plastics and the like, although the cleaning method and apparatus described herein may be useful for other materia1s as well. Thus, the present invention is concerned with the recycling of these materials in industrial applications. The present invention finds particular usefulness in recycling "clay pigeons" which are commonly used in the popular shotgun sport of trap and skeet shooting. While this invention is described in reference to recycling these clay targets which are formed of a thermoset material, it should be appreciated that the scope of this disclosure may readily be adapted for use in other industrial recycling activities where materials or objects for recycling have become contaminated by debris, dirt, sand or the like.
Currently, a thermoset material is used to manufacture clay targets and comprises a mixture of resin, such as coal tar or petroleum pitch, and calcium carbonate (lime). The resin and lime are mixed in proportions to provide a desired target weight and brittleness. In the manufacturing process, the resin is melted and the lime, in powder form, is mixed with the melted resin to form a homogenous mixture that is then heated to approximately 350.degree. F. The manufacturer casts (thermosets) the material in the desired shape by means of a mold which is removed from the clay target after the material cools. Manufacturers currently employ virgin material to produce these clay targets which results in a consumption of material resources.
The sport of trap and skeet shooting utilizes these clay targets wherein the argets are mechanically launched and contestants fire at the targets while they are in flight. Since the targets are made of a brittle material, they break into fragments or shards when hit by a pellet or upon impact with the ground should they not be struck. Substantial quantities of these shards from used targets will build up at a typical gun range, with these shards becoming mixed with a variety of debris, such as shell wadding material, shells, twigs, paper, nails and the like as well as other contaminants such as dirt and sand.
When attempts are made at recycling the clay target shards, several problems are encountered. Since the materials must be pulverized for refabrication, the presence of durable debris or contaminants can cause substantial damage to the reprocessing equipment. Even if these materials are removed, other contaminants may degrade the strength of the new fabricated target which must be strong enough to withstand the mechanical launching process but weak and brittle enough to shatter when hit by even one shell pellet. The presence of contaminants in the recycled material can degrade the strength of the refabricated target. Thus, target manufacturers facturers rely on virgin materials, as discussed above, while large quantities of used shards remain available.
Accordingly, there is a need for an apparatus and method that can remove debris and contaminant materia1s so that such shards may be pulverized or crushed and reused. There is further a need for such an apparatus and invention that can economically clean shards so that the shards may be recycled in a cost-effective manner. Such a method and apparatus would be beneficial from an environmental point of view in eliminating the need for a total use of virgin material while at the same time eliminating the large build-up of shards at shooting ranges.